A storage device (drive enclosure (DE)) that includes a plurality of hard disk drives (HDDs) and a disk control device that controls the HDDs is known. In addition, a Redundant Arrays of Inexpensive Disks (RAID) device that includes a plurality of storage devices is known.
The HDDs are storage medium driving devices that each have a structure in which a plurality of storage media (called platters) that are formed by coating or evaporating a magnetic material on metal are stacked at regular intervals. The HDDs each read and write data from and in the platters by causing a spindle motor (SPM) to rotate the stacked platters at a high speed and causing heads to be placed close to the platters.
The heads are located at ends of head arms. The heads are moved to inner and outer sides of the platters by a voice coil motor (VCM) and thereby positioned above target tracks of the platters.
The HDDs each include the spindle motor (SPM) and the voice coil motor (VCM). Thus, a vibration occurs in each of the HDDs owing to driving of the motors. The DE that includes the plurality of HDDs receives vibrations of the HDDs and generates a large vibration.
A storage system includes a plurality of DEs located on storage shelves included in a chassis. Vibrations that are generated by the DEs are transferred to the storage shelves so that a resonance occurs between the DEs in some cases. When the vibrations and the resonance are transferred to the DEs, the heads that are included in the HDDs included in the DEs vibrate. Thus, the heads are not appropriately positioned above target positions of the platters in some cases, and an access error may occur during reading of data or during writing of data.
In recent years, there has been a demand for HDDs to have large capacities and read and write data at high speeds, such HDDs has been rapidly developed, and the structures of the HDDs have become complicated. In order to increase the capacity of an HDD, the number of platters included in the HDD is increased as an example. In addition, in order to read and write data at a high speed, the numbers of revolutions of the platters are increased and the seek speeds of the heads are increased as examples.
In addition, yaw angles of the heads vary depending on target tracks of the platters owing to the structure of the HDD. The heads are provided for the platters. The number of platters, the number of heads and installation positions of the heads vary depending on the type of the HDD. The HDD includes a plurality of structural elements and control-related elements. Thus, it is not easy to simulate a vibration that occurs during an operation of the HDD.
In addition, regarding a DE that includes a plurality of HDDs, the number of parameters that are related to a vibration increases in response to an increase in the number of the HDDs. Thus, it is very, difficult to simulate a vibration that occurs during access operations of the HDDs included in the DE.
Adjusting the thickness of a metal sheet of a chassis of the DE on the basis of an experimental rule or changing a material of a case for housing the HDDs in the DE on the basis of an experimental rule makes a vibration unlikely to occur in the DE.
Japanese Laid-open Patent Publications Nos. 2003-228956 and 2-134793 are technical documents that are related to the aforementioned techniques.